Line measuring device with correcting mechanism



y 22, 1952 R. B. BASHAM ETAL 2,604,526

LINE MEASURING DEVICE WITH CORRECTING MECHANISM Filed Jan. 14, 1950 GEAR SIZE CORRECTION FT. PER IOOOFT.

RAYMOND B BAS CHARLES wI MACUNE Gttorneg Patented July 22, 1952 7 LINE MEASURING DEV-ICE was ooaanc rmo MECHANISM Raymond B."Basham and Charles W. Macune, Fort Worth, Tex., assignors to Westronics, Inc., a Fort Worth, Tex., a corporation of Texas Application January 14, 1950,'SerialNo. 138,662

This invention relates to line measuring apparatus. Although the invention has many ap- 'plications, it is particularly useful for determining the depth of a mechanism attached to a cable and lowered in a well.

In servicing oil and gas wells it is often important to have an instrument or device lowered to an exact depth, as when perforating casing opposite an oil or gas bearing formation, locating cementing plugs, and when logging or surveying the geological characteristics of a well. The general practice of determining the depth to which an instrument has been lowered in a well ,hasbeen to run a line or cable supporting the instrument over a sheave and counting the revolutions of the latter with a mechanical meter. However, the referred to method was objectionable in that it did not provide for inaccuracies in the diameters of the sheave or line. For example, if the diameter of a sheave was slightly oversize or undersize, the resulting count would inaccurately locate the instrumentabove or below the indicated depth. All sheave wheels used for the described purpose are intended to be of an accurately known diameter, but duefto wear, or other reasons, these diameters do not remain the same as originally made. The diameter of the line or cable also afiects'the accuracy of, the results obtained by counting the revolutions of the sheave. Operators of. well servicing equipment usually know the exact inaccuracies of the diameters of the sheaves and the lines since they may be determined by actual tests in wells of known depth. When servicin a well it is impractical to make allowance for these corrections mathematically as this would be time consuming, and therefore undesirable. In as much as several thousand'feet of line may be lowered into a well at one time, a slight inaccuracy in the sheave or cable diameter, or both, may result in the instrument being located incorrectly with respect to the intended depth. To compensate for such inaccuracies, the use of gear trains alone would involve a complicated gear train-of .mine the depth of said mechanism or instrument.

4 Claims. (Cl. 177351) Another object of the invention is to provide a compact mechanism for the purposes referred to in'the foregoing object. 7

Another object of the invention is to provide, in a line measuring device of the described class,

"a relatively simple device which avoids the use of a; large number of gears for making only slight correction changes in the gear ratio.

A further object of the invention is to provide :a'selsyn operated counter for conveniently determining'the number of revolutions of a sheave,

and at the same time, provide forcorrections of known inaccuracies in 'the diameters of the sheave or line. I 7

These and other objects of the invention will become apparent from the followingdescription,

and from the accompanying drawings, wherein:

Figure 1 is a schematic view showing a portion of a well in section, and having ajsheave thereabove for lowering a line and instrument attached thereto into said well, together with a wiring diagram of the present invention and showing the same mechanically coupled with vthe sheave.

' Figure 2 is a plan view of the line compensator unit and counter.

Figure 3 is a front elevation of Figure 2.

""Figure 4 is a gear chart showing a selection of gears for correcting the known errors.

In the drawings, the numeral In indicatesv a well casing in the earth ll, and into which a well surveying instrument I2 is lowered by means of af cableor line [3. The line I3 passes over a sheave M which is rotatably supported above the earths surface by means of a bracket [5 attached ,to the; well derrick (not shown).

Agear I6 is secured to the center of the sheave I4 and meshes with .the driven gear I1 ofa selsyn transmitter I8. Current supply lines I9 are connected with the rotor of the selsyn transmitter 18. The stator fields of the transmitter I8 are connected with a selsyn repeater 20 after passin through the fields of a selsyn differential 2!. The rotor of'the repeater 2041s also connected with the current supply-by lines 22. The rotor of the repeater is mechanically coupled with a mechanical counter 23, as shown in the upper portion of Figure 2.. The described connections between the transmitter I8 and the differential 2|, and between the difierential 2i and the repeater 20, are

trated in detail, nor are they referred to by number.

The stator fields of an additional selsyn repeater 26 are connected with line 24 by additional lines 21. The additional repeater 26, as well as the selsyn differential 2|, is mounted on a rectangular box-like frame, as shown in Figure 2. The rotor of the selsyn repeater 26 is mechanicallycoupled with a wormjournaled in the frame 2.8. .I'he'.worm,29 drives aworm gear 30 mounted on a shaft 3! which is also journaled in the frame 28, and is supported at one end thereof by a bracket 32. The shaft! is also provided with a worm 33 which'drives-another worm gear 34 mounted on a transverse shaft-35. Preferably, the ratio betweentherdrivenrotor: of the additional or intermediateirepeater 1.26: and the last described shaft i 1000 to l1 soxto simplify the selection of spur ,gears referred to in the chart, Figure 4. In View of'the low gear ratio between the worm 29 and the driven worm gear 34, it is not necessary to supply power to the -,rotor ,,of the intermediate repeater --26, although 7- such power may be: supplied.- if desired.

The outer end of the-.lastdescribedvshaft 35 projectsaoutwardly from 'the face 'of the frame r28 where it is provided --with 'a --gear 36 which ond-andthirdreferred .togears31 and 38 are mounted. on asinglelstub shaft vMandarekeyed to each other. Thefourthreferredto gear 39 .is an idler ,gear and is .arranged -.to v.mesh with the gear 38 and the gear 40. The .idler ,gear

. 39. issupportedon -a. bracket 43. hingedlymounted L ,on zthfi. .frame :18 -by means .of :a vprojecting ,stub

.shaftM. ..For.convenience.in, identifyingthe re- -running .the line l3- over-.the.-sheave l4. .Breferably, the ratio of the gears connected with the sheave. M .is.-such that .the circumference ,of lthesheaveis ,easilycalculatedin feet. .The selsyn repeater .210 connected with the counter -23 .is .driven by .theiselsyn transmitter |.8 .after the current therefrom passes through .the.selsyn difierential 2!. The knownerrorLinthe .diamv.eter of the sheave 1-4 or the. cable l3v isrcorrected by an arrangement of .the gears,A,TB, iCiancL'ID inaccordance .Withthechartillustrated lin Eigure '4. ,For example,;ifalcorrectionaofqplus one 'footper 1000 feet. is required, the .gears A, .B, C .an'dD .w'illihave, .respectively, 20, 40, 40 .and 120' teeth. In other worfdsQthe 110.00 to .-1 gear ratio of thefixed, re'duction,, gear, comprising the worms and gears 29, '30, 34 and 35, are 'transimitted 'mechanical'ly "to the shaft '4! which .is mechanically coupled .with the .rotor oft-the -slsyn differential 2|. Thus, *only .the ratio .1000 to 1 Listeifecitive. .If acorrection of plus .1 foot per-I000 feetfisnecessaryithe gears A,'B, C and ,D will respectively have 20, 210,12 .jand "60 teeth 'andqa .ratiozof 10 toil 'withrespect to gears-A. "Since-the worm gear'34.is not a;ratio of'1000 "to 'lpwith respectito'theworm 'gear..29, 'the total :gea'r ratiolbetween the worm "2-9 of the driven gear]? will be'1'0,'000';to 1.

Although a minus correction coul'dlbe obtained reversingthe'order of gears'such'minus correction. may beimore' easily obtained by revers- 'in'g'the position of the "connecting wires 2lso as to rotate the rotor of the intermediate repeater 26 in an opposite direction.

By reason of the described construction and arrangement, it is obvious that the transmitter I8 would ordinarily rotate the rotor of the selsyn repeater 20 an equal number of revolutions.

If it were not for the :described gearuarrange- 'ment, the selsyn differential would not rotate and would merely act as a transformer and would have the same efi'ect as if there were direct electrical connections therethrough. How- 'ever, the mechanical coupling between the rotorof the additional or intermediate repeater with therotorof the differential 2! imparts a rotationito the latter which, in turn, is electrically transferred to the rotor of the repeater .sheave-adaptedito beturned by the'line to be measured, a selsyn transmitter connected with and driven by saidsheave a selsyn repeater having an indicator connected therewith, a.selsyn differential electrically connecting said transmitterand-saifd repeater, an additional selsyn repeater electrically connected with said trans- "mi-tter, and a gear train connecting the rotor of said additional repeater with the rotor of said differential.

.2. A line measuring apparatus comprising ,a selsyn transmittenadaptedto be connected with and rotated by the line tobe measured, .a-selsyn repeater having an indicator connected therewith, .a selsyn differential electrically connecting said transmitter and said repeater, an additional selsyn repeater electrically connected with said transmitter, and aJgear train connecting the rotor of said .additional repeater with the rotor of said differential.

3.. Ailine measuring apparatus comprising ..a selsyn transmitter adapted'to beconnected with and rotated'by the line'to be measured,.a selsyn :repeater :having an indicator connected therewith, a 'selsyn differential electrically con- .necting said 'transmitterwith said repeater, .an additional 'selsynrepeater electrically connected with saidtransmitter, a worm gear mechanism connected'with the rotor of said additional "re,-

:peater, an'da ,gear'train connecting .said worm "gearlmechanismwith'the rotor 'of said differential.

'4. A line 'measuring apparatus as defined in claim 3,;an'd wherein said wormgearmechanism has -a.gear"ratio in a'multiple of 10"to l.

RAYMOND .B. 'BASI-IAM. CHARLES W. MACUNE'.

QREFEREN'CES .GITED The following references are of record 1.111 :the

le 10fthis :patent: 1 

